With the increase in demands of users for high-speed data transmission, LTE is undoubtedly one of the most competitive wireless transmission technologies. In LTE, a user equipment may be in two states, that is, an RRC_CONNECTED state and an RRC_IDLE state. In a case where uplink synchronization is performed during the switch process (or performed for a user equipment losing uplink synchronization), or in a case where there is no sufficient resources for transmitting a scheduling request, a random access procedure is to be performed in order to cause the user equipment to transit from the RRC_IDLE state to the RRC_CONNECTED state or to recover from a link failure.
However, a maximum time interval currently required for a user equipment to transit from the RRC_IDLE state to the RRC_CONNECTED state is 50 ms. In addition, there may be a conflict in the random access procedure, which prolongs the random access procedure. Therefore, for some special services such as a V2X security service with a high real-time requirement and a service on unlicensed resources in which the resource availability changes rapidly, a time delay due to random access failure may result in a serious consequence. In order to meet the requirement in an application scenario with a high real-time requirement and to improve the communication efficiency, the random access procedure is desired to be accelerated.